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Objective To investigate the epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing unilateral mastectomy. Study design Prospective, randomized, blinded, clinical study. Animals A total of 22 bitches scheduled to undergo unilateral mastectomy for mammary tumor excision. Methods Dogs were anesthetized with acepromazine (0.02 mg kg–1) and morphine (0.3 mg kg–1) intramuscularly, propofol intravenously (IV) and isoflurane. Prior to the beginning of surgery, dogs were randomly administered one of three epidural treatments: ropivacaine (0.75 mg kg–1) with morphine (0.1 mg kg–1) (group RM, n = 7); ropivacaine with xylazine (0.1 mg kg–1) (group RX, n = 8); or ropivacaine with morphine and xylazine (group RMX, n = 7). Cardiopulmonary variables and the expired concentration of isoflurane (F e ′Iso) were recorded intraoperatively. Meloxicam (0.1 mg kg–1) was administered IV during skin closure. Postoperative pain scores were evaluated with the Glasgow composite measure pain scale short form for 24 hours, and rescue analgesia with morphine (0.5 mg kg–1) was administered intramuscularly when pain scores were ≥ 6/24. Results F e′ Iso was significantly higher in group RM than in groups RX and RMX. Heart rate decreased significantly in groups RX and RMX, but blood pressure remained within acceptable values. The number of dogs administered rescue analgesia within 24 hours was significantly higher in group RX (seven out of eight dogs, 87.5%) than in groups RM (one out of seven dogs, 14.3%; p = 0.01) and RMX (two out of seven dogs, 28.6%; p = 0.04). Time to standing was significantly longer in group RX than in group RM. Conclusions and clinical relevance All epidural treatments provided adequate antinociception with minimal cardiovascular adverse effects during mastectomy. The inclusion of morphine (groups RM and RMX) provided the best postoperative analgesia. Owing to the undesirable effect of xylazine on ambulation, the combination ropivacaine–morphine appeared to provide greater benefits in bitches undergoing unilateral mastectomy.

Objectives To investigate the extent of vatinoxan distribution into sheep brain, and whether vatinoxan influences brain concentrations of xylazine; and to examine the utility of cerebrospinal fluid (CSF) as a surrogate of brain tissue concentrations for vatinoxan and xylazine. Study design Randomised, blinded, experimental study. Animals A total of 14 adult female sheep. Methods Sheep were randomly allocated into two equal groups and premeditated with either intravenous (IV) vatinoxan (750 mu g kg(-1), VX) or saline (SX) administered 10 minutes before IV xylazine (500 mu g kg(-1)). Sedation was subjectively assessed at selected intervals before and after treatments. At 10 minutes after xylazine administration, a venous blood sample was collected and the sheep were immediately euthanised with IV pentobarbital (100 mg kg(-1)). Plasma, CSF and brain tissues were harvested, and concentrations of vatinoxan and xylazine were quantified using liquid chromatography-tandem mass spectrometry. Drug ratios were then calculated and the data were analysed as appropriate. Results The brain-to-plasma and CSF-to-plasma ratios of vatinoxan were 0.06 +/- 0.013 and 0.05 +/- 0.01 (mean +/- standard deviation), respectively. Xylazine brain concentrations were not significantly different (835 +/- 262 versus 1029 +/- 297 ng g(-1) in groups VX and SX, respectively) and were approximately 15-fold higher than those in plasma. The CSF-to-brain ratio of vatinoxan was 0.8 +/- 0.2, whereas xylazine concentrations in the brain were approximately 17-fold greater than those in CSF, with and without vatinoxan. Conclusions and clinical relevance Vatinoxan did not significantly affect sedation with xylazine or the concentrations of xylazine in the brain. CSF is not a good predictor of xylazine concentrations in the brain, whereas vatinoxan concentrations were concordant between the brain and CSF, using the dosages in this study.

Objective To elucidate the antinociceptive, physiologic and biochemical effects of electroacupuncture (EA) and xylazine in hybrid goats. Study design Prospective experimental study. Animals A total of 30 female hybrid goats aged 1–2 years and weighing 25 ± 2.9 kg (mean ± standard deviation). Methods The goats were divided into five groups and administered xylazine (0.1 mg kg−1; group XYL.1), xylazine (0.3 mg kg−1; group XYL.3), EA (group EA), EA + xylazine (0.1 mg kg−1; group XYL.1-EA) and 0.9% saline (0.3 mL; control group CON). Nociceptive threshold and serum glucose concentration were measured at time 0 and at 15, 30, 45, 60 minutes and 24 hours after treatment. Nociceptive threshold was measured by passing potassium ions through the skin using potassium iontophoresis. Mean arterial pressure (MAP), heart rate (HR), respiratory frequency (fR) and rectal temperature (RT) were recorded at times 0 and at 5, 10, 15, 20, 30, 45, 60 minutes and 24 hours. Repeated-measures analyses were performed for each response variable; p Results Antinociceptive effects in groups XYL.1 and XYL.3 were increased significantly at 15–60 minutes compared with group CON. Antinociceptive effect was higher in group XYL.1-EA than groups XYL.1 or EA at 15–60 minutes (p Conclusions and clinical relevance The XYL.1 and EA combination was effective for antinociception with minimum physiologic alteration, suggesting that the combination may be a new and effective strategy for pain relief during clinical procedures in goats.

To compare effects of intravenous (IV) alfaxalone with ketamine-xylazine combination on anaesthetic induction, recovery and cardiopulmonary variables in mute swans. Randomized, controlled, clinical study. A group of 58 mute swans. Swans were given either alfaxalone (10 mg kg ; group A) or a combination of ketamine (12.5 mg kg ) and xylazine (0.28 mg kg ) (group KX) IV. Heart and respiratory rates, end-tidal carbon dioxide and peripheral haemoglobin oxygen saturation were recorded at 5 minute intervals during anaesthesia. Time from anaesthetic induction to intubation, from cessation of isoflurane to extubation, to lifting head, sternal recumbency and absence of head/neck ataxia were recorded. Anaesthetic and recovery quality were scored (1 = very poor; 5 = excellent). Data are presented as median (interquartile range). Significance was set at p < 0.05. In group A, 44% (12/27) of swans required mechanical ventilation for 2-14 minutes versus 3.2% (one/31) of swans in group KX (p = 0.0002). Heart rate was higher in group A than in group KX [146 (127-168) versus 65.5 (56-78) beats minute , respectively; p < 0.0001]. The isoflurane concentration required to maintain anaesthesia was higher in group A than in group KX [2.5% (2.0-3.0%) versus 1.5% (1.0-2.0%), respectively; p = 0.0001]. Time from cessation of isoflurane administration to lifting head was significantly longer in group A than in group KX [12 (9-17) versus 6 (4-7.75) minutes, respectively; p < 0.0001]. Anaesthesia quality scores were significantly better in group KX than in group A [4 (4-5) versus 4 (3-4), respectively; p = 0.0011], as were recovery scores [4 (3-5) versus 2 (2-3), respectively; p = 0.0005]. Alfaxalone is a suitable anaesthetic induction agent for use in mute swans. There is a greater incidence of postinduction apnoea and a higher incidence of agitation on recovery with alfaxalone than with ketamine-xylazine. [Abstract copyright: Copyright © 2021 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.]

Objective To investigate the effect of metamizole on physiologic variables in calves undergoing surgical extirpation of the navel during anaesthesia using xylazine, ketamine and isoflurane. Study design Double-blind, randomized trial. Animals A total of 26 calves. Methods Calves with uncomplicated umbilical hernias and otherwise clinically healthy were randomly allocated to one of two groups: the control group (CG) and metamizole group (MG). All calves were administered meloxicam (0.5 mg kg–1) intravenously (IV) 150 minutes before skin incision (SI). Animals were premedicated with xylazine (0.2 mg kg–1) intramuscularly 50 minutes before SI. Anaesthesia was induced with ketamine (2 mg kg–1) IV 30 minutes before SI and maintained with isoflurane in oxygen. MG calves were given metamizole (40 mg kg–1) IV 60 minutes before SI. CG calves were administered an equivalent volume of saline. Heart rate (HR) and mean arterial blood pressure (MAP) were recorded from 5 minutes before SI until the end of anaesthesia (60 minutes after SI). Blood samples for determination of the plasma cortisol concentration (PCC) were drawn 60 minutes before SI and at 5, 30, 60, 150, and 510 minutes after SI. Results In both groups, PCC increased during surgery and decreased after surgery. PCC was consistently lower in MG than in CG and was significantly (p = 0.0026) lower at 150 minutes after SI in the MG. Overall, the mean PCC in MG was 10.9 nmol L–1 lower than that in CG (p = 0.01). In both groups, HR decreased during anaesthesia, whereas MAP increased, albeit with no statistically significant (p > 0.05) differences between groups. Conclusions and clinical relevance Our study results suggest that a single preoperative dose of metamizole may have a positive impact on intra- and immediate postoperative analgesia by reducing PCC when used as an indicator of nociception.

Objective To evaluate the anesthetic and cardiopulmonary effects of xylazine–alfaxalone anesthesia in donkey foals undergoing field castration. Study design Prospective clinical study. Animals A group of seven standard donkeys aged [median (range)] 12 (10–26) weeks, weighing 47.3 (37.3–68.2) kg. Methods Donkeys were anesthetized with xylazine (1 mg kg−1) intravenously (IV) followed 3 minutes later by alfaxalone (1 mg kg−1) IV. Additional doses of xylazine (0.5 mg kg−1) and alfaxalone (0.5 mg kg−1) IV were administered as needed to maintain surgical anesthesia. Intranasal oxygen was supplemented at 3 L minute−1. Heart rate (HR), respiratory rate (fR) and mean arterial pressure (MAP) by oscillometry were recorded before drug administration and every 5 minutes after induction of anesthesia. Peripheral oxygen saturation (SpO2) was recorded every 5 minutes after induction. Time to recumbency after alfaxalone administration, time to anesthetic re-dose, time to first movement, sternal and standing after last anesthetic dose and surgery time were recorded. Induction and recovery quality were scored (1, very poor; 5, excellent). Results Median (range) induction score was 5 (1–5), and recovery score 4 (1–5). Overall, two donkeys were assigned a score of 1 (excitement) during induction or recovery. HR and MAP during the procedure did not differ from baseline. fR was decreased at 5 and 10 minutes but was not considered clinically significant. SpO2 was Conclusions and clinical relevance Xylazine–alfaxalone anesthesia resulted in adequate conditions for castration in 12 week old donkeys. While the majority of inductions and recoveries were good to excellent, significant excitement occurred in two animals and may limit the utility of this protocol for larger donkeys. Hypoxemia occurred despite intranasal oxygen supplementation.

Objective To compare the sedative and clinical effects of intravenous (IV) administration of dexmedetomidine and xylazine in dromedary calves. Study design Experimental, crossover, randomized, blinded study. Animals A total of seven healthy male dromedary calves aged 14 ± 2 weeks and weighing 95 ± 5.5 kg. Methods Calves were assigned three IV treatments: treatment XYL, xylazine (0.2 mg kg−1); treatment DEX, dexmedetomidine (5 μg kg−1); and control treatment, normal saline (0.01 mL kg−1). Sedation scores, heart rate (HR), respiratory rate (fR), rectal temperature (RT) and ruminal motility were recorded before (baseline) and after drug administration. Sedation signs were scored using a 4-point scale. One-way anova and Mann–Whitney U tests were used for data analysis. Results Calves in treatments XYL and DEX were sedated at 5–60 minutes. Sedation had waned in XYL calves, but not DEX calves, at 60 minutes (p = 0.037). Sedation was not present in calves of any treatment at 90 minutes. HR decreased from baseline in XYL and DEX at 5–90 minutes after drug administration and was lower in DEX than XYL at 5 minutes (p = 0.017). HR was lower in DEX (p = 0.001) and XYL (p = 0.013) than in control treatment at 90 minutes. fR decreased from baseline in XYL and DEX at 5–60 minutes after drug administration and was lower in DEX than XYL at 5 minutes (p = 0.013). RT was unchanged in any treatment over 120 minutes. Ruminal motility was decreased in XYL at 5, 90 and 120 minutes and absent at 10–60 minutes. Motility was decreased in DEX at 5, 10 and 120 minutes and was absent at 15–90 minutes. Conclusion and clinical relevance The duration of sedation from dexmedetomidine (5 μg kg–1) and xylazine (0.2 mg kg–1) was similar in dromedary calves.

Objective To investigate the influence of ketamine on plasma cortisol concentration (PCC) in calves. Study design Prospective, randomized experimental study. Animals A total of 41 healthy, predominantly cross-bred calves, aged 3–4 months. Methods Calves were premedicated with intramuscular xylazine (0.2 mg kg–1) and randomly divided into four groups. The control group (CONT) received saline (after 10, 20 and 30 minutes), whereas groups K1, K2 and K3 were injected intravenously once, twice or thrice, respectively, with 4 mg kg–1 of ketamine at 10 minute intervals. Blood samples were collected at fixed time points and analysed to determine the PCC; furthermore, the plasma concentrations of ketamine and norketamine were assessed after a single ketamine administration in group K1. The pharmacokinetic parameters of ketamine and norketamine were calculated as plasma concentrations versus time. Results All groups showed significant (p Conclusions and clinical relevance Our results showed that ketamine increases the plasma concentration of cortisol in xylazine-treated calves. Thus, the previous treatment of subjects needs to be considered in studies using plasma/serum cortisol concentrations as an indicator of pain.

Objective To determine the suitability of alfaxalone total intravenous (IV) anaesthesia in horses and concurrently evaluate infusion rates, cardiovascular effects, pharmacokinetics and the quality of the anaesthetic recovery period. Study design Prospective, experimental study. Animals Eight Standardbred horses. Methods Horses were premedicated with IV acepromazine (0.03 mg kg–1) and xylazine (1 mg kg–1) and anaesthesia was induced with guaifenesin (35 mg kg–1) and alfaxalone (1 mg kg–1). Anaesthesia was maintained for 180 minutes using an IV infusion of alfaxalone at a rate determined by a horse’s response to a supramaximal electrical noxious stimulus. Venous blood samples were regularly collected to determine alfaxalone plasma concentrations and for pharmacokinetic analysis. Cardiopulmonary variables were monitored and the quality of the anaesthetic recovery period scored. Results The median (range) alfaxalone infusion rate was 3.1 (2.4–4.3) mg kg–1 hour–1. The mean ± standard deviation plasma elimination half-life, plasma clearance and volume of distribution for alfaxalone were 41 minutes, 25 ± 6.3 mL minute–1 kg–1 and 1.6 ± 0.5 L kg–1, respectively. During anaesthesia, mean arterial blood pressure was maintained above 70 mmHg in all horses. Cardiac index reached a minimum value (68% of baseline values) immediately after induction of anaesthesia and was maintained between 74% and 90% of baseline values for the remainder of the anaesthetic protocol. Following the cessation of the alfaxalone infusion, six of eight horses exhibited muscle tremors and paddling. All horses stood without incident on the first or second attempt with a median recovery score of 4.5 (good to excellent). Conclusions and clinical relevance Anaesthesia in horses can be maintained with an infusion of alfaxalone at approximately 3 mg kg–1 hour–1. The alfaxalone infusion rates used resulted in minimal haemodynamic changes and good recovery quality. Mean alfaxalone plasma concentration was stable over the infusion period and clearance rates were similar to previously published single-dose alfaxalone studies in horses.

To determine the effects of intravenous ethyl pyruvate, an anti-inflammatory with putative benefits in horses with endotoxemia, on cardiopulmonary variables during anesthesia and the quality of anesthetic recovery.Randomized, crossover, blinded experimental design.A total of six healthy Standardbred geldings, aged 13 ± 3 years and weighing 507 ± 66 kg (mean ± standard deviation).Horses were anesthetized for approximately 90 minutes on two occasions with a minimum of 2 weeks apart using xylazine for sedation, ketamine and diazepam for induction, and isoflurane in oxygen for maintenance. Lactated Ringer's solution (LRS; 10 mL kgAll horses completed the study. No significant differences were detected between the ethyl pyruvate and LRS treatments for either the cardiopulmonary variables or quality of recovery from anesthesia.The results suggest that intravenous ethyl pyruvate can be administered to healthy anesthetized horses with minimal impact on the cardiopulmonary variables studied or the quality of recovery from anesthesia.

Objective To compare the sedative effects of intramuscular xylazine alone or combined with levomethadone or ketamine in calves before cautery disbudding. Study design Randomized, blinded, clinical trial. Animals A total of 28 dairy calves, aged 21 ± 5 days, weight 61.0 ± 9.3 kg (mean ± standard deviation). Methods Calves were randomly allocated to three groups: xylazine (0.1 mg kg−1) and levomethadone (0.05 mg kg−1; group XL), xylazine (0.1 mg kg−1) and ketamine (1 mg kg−1; group XK) and xylazine alone (0.2 mg kg−1; group X). Local anaesthesia (procaine hydrochloride) and meloxicam were administered subcutaneously 15 minutes after sedation and 15 minutes before disbudding. The calves’ responses to the administration of local anaesthesia and disbudding were recorded. Sedation scores were evaluated at baseline and at intervals up to 240 minutes postsedation. Times of recumbency, first head lift and first standing were recorded. Drug plasma concentrations were measured. Results Data were obtained from 27 animals. All protocols resulted in sedation sufficient to administer local anaesthesia and to perform disbudding. Sedation scores significantly correlated with drug plasma concentrations (p ≤ 0.002). Times to recumbency did not differ among protocols (2.8 ± 0.3, 3.1 ± 1.1 and 2.1 ± 0.8 minutes for groups XL, XK and X, respectively), whereas interval from drug(s) administration until first head lift was significantly shorter in group XK than X (47.3 ± 14.1, 34.4 ± 5.3 and 62.6 ± 31.9 minutes for groups XL, XK and X, respectively). The area under the time-sedation curve was significantly greater in group X than XK or XL (754 ± 215, 665 ± 118 and 1005 ± 258 minutes for groups XL, XK and X, respectively). Conclusion and clinical relevance Levomethadone or ketamine with a low dose of xylazine produced short but sufficient sedation for local anaesthesia and disbudding with minimum resistance.

Objective To compare the efficacy of single-breath continuous positive airway pressure manoeuvre (CPAP-M) with inhaled salbutamol, and a combination of both. Study design Randomized, clinical study. Animals A total of 62 client-owned horses (American Society of Anesthesiologists status III–V) anaesthetized for laparotomy. Methods Horses were premedicated with intravenous (IV) xylazine (0.4–0.6 mg kg–1), anaesthesia was induced with midazolam (0.06 mg kg–1 IV) and ketamine (2.2 mg kg–1 IV) and maintained with isoflurane in oxygen using volume-controlled ventilation without positive end-expiratory pressure. If PaO2 was i O2 ratio and estimated shunt fraction (F-shunt) were derived from data obtained from arterial blood gas measurements. Dynamic compliance (Cdyn) was calculated from variables recorded at the moment of arterial blood analysis. Fisher’s exact tests compared success rates between treatments, and linear models were performed to test whether the treatment modified the values of the measurements; p Results Salbutamol was the first intervention in 28 horses and was effective in 22 horses. CPAP-M was the first intervention in 34 horses and was effective in 26 horses. CPAP-M after salbutamol was performed in six horses, with four responders, and salbutamol after CPAP-M was administered to eight horses, with one responder. Salbutamol, but not CPAP-M, significantly decreased F-shunt. Both salbutamol and CPAP-M significantly increased Cdyn. Conclusionsand clinical relevance Salbutamol and CPAP-M were comparably effective in improving oxygenation and Cdyn in anaesthetized horses with PaO2

Objective To evaluate perioperative stress-related hormones in isoflurane-anesthetized horses administered infusions of dexmedetomidine alone or with butorphanol or remifentanil, compared with ketamine–morphine. Study design Randomized, prospective, nonblinded clinical study. Animals A total of 51 horses undergoing elective surgical procedures. Methods Horses were premedicated with xylazine, anesthesia induced with ketamine–diazepam and maintained with isoflurane and one of four intravenous infusions. Partial intravenous anesthesia (PIVA) was achieved with dexmedetomidine (1.0 μg kg–1 hour–1; group D; 12 horses); dexmedetomidine (1.0 μg kg–1 hour–1) and butorphanol bolus (0.05 mg kg–1; group DB; 13 horses); dexmedetomidine (1.0 μg kg–1 hour–1) and remifentanil (3.0 μg kg–1 hour–1; group DR; 13 horses); or ketamine (0.6 mg kg–1 hour–1) and morphine (0.15 mg kg–1, 0.1 mg kg–1 hour–1; group KM; 13 horses). Infusions were started postinduction; butorphanol bolus was administered 10 minutes before starting surgery. Blood was collected before drugs were administered (baseline), 10 minutes after ketamine–diazepam, every 30 minutes during surgery and 1 hour after standing. Mean arterial pressure (MAP), pulse rate, end-tidal isoflurane concentration, cortisol, nonesterified fatty acids (NEFA), glucose and insulin concentrations were compared using linear mixed models. Significance was assumed when p Results Within D, cortisol was lower at 120–180 minutes from starting surgery compared with baseline. Cortisol was higher in KM than in D at 60 minutes from starting surgery. Within all groups, glucose was higher postinduction (except DR) and 60 minutes from starting surgery, and insulin was lower during anesthesia and higher after standing compared with baseline. After standing, NEFA were higher in KM than in DB. In KM, MAP increased at 40–60 minutes from starting surgery compared with 30 minutes postinduction. Conclusions and clinical relevance Dexmedetomidine suppressed cortisol release more than dexmedetomidine–opioid and ketamine–morphine infusions. Ketamine–morphine PIVA might increase catecholamine activity.

Objective Various drugs administered to horses undergoing surgical procedures can release histamine. Histamine concentrations were evaluated in horses prepared for surgery and administered butorphanol or morphine intraoperative infusions. Study design Prospective studies with one randomized. Animals A total of 44 client-owned horses. Methods In one study, anesthesia was induced with xylazine followed by ketamine–diazepam. Anesthesia was maintained with guaifenesin–xylazine–ketamine (GXK) during surgical preparation. For surgery, isoflurane was administered with intravenous (IV) morphine (group M: 0.15 mg kg–1 and 0.1 mg kg–1 hour–1; 15 horses) or butorphanol (group B: 0.05 mg kg–1 and 0.01 mg kg–1 hour–1; 15 horses). Histamine and morphine concentrations were measured using enzyme-linked immunoassay before opioid injection (time 0), and after 1, 2, 5, 30, 60 and 90 minutes. In a subsequent study, plasma histamine concentrations were measured in 14 horses before drug administration (baseline), 15 minutes after IV sodium penicillin and 15 minutes after starting GXK IV infusion. Statistical comparison was performed using anova for repeated measures. Pearson correlation compared morphine and histamine concentrations. Data are presented as mean ± standard deviation. Significance was assumed when p ≤ 0.05. Results With histamine, differences occurred between baseline (3.2 ± 2.4 ng mL–1) and GXK (5.2 ± 7.1 ng mL–1) and between baseline and time 0 in group B (11.9 ± 13.4 ng mL–1) and group M (11.1 ± 12.4 ng mL–1). No differences occurred between baseline and after penicillin or between groups M and B. Morphine concentrations were higher at 1 minute following injection (8.1 ± 5.1 ng mL–1) than at 30 minutes (4.9 ± 3.1 ng mL–1) and 60 minutes (4.0 ± 2.5 ng mL–1). Histamine correlated with morphine at 2, 30 and 60 minutes. Conclusions and clinical relevance GXK increased histamine concentration, but concentrations were similar with morphine and butorphanol.

Objective To evaluate the oxygen reserve index (ORI) as a noninvasive estimate of the PaO2 during moderate hyperoxaemia [100–200 mmHg (13.3–26.6 kPa)], and to determine ORI values identifying PaO2 > 100, > 150 (20.0 kPa) and > 200 mmHg in anaesthetized donkeys with an inspired fraction of oxygen (F i O2) > 0.95. Study design Prospective observational study. Animals A group of 28 adult standard donkeys aged (mean ± standard deviation) 4 ± 2 years and weighing 135 ± 15 kg. Methods Donkeys were sedated intramuscularly with xylazine and butorphanol; anaesthesia was induced with ketamine and diazepam and maintained with isoflurane in oxygen. An adhesive sensor probe was applied to the donkey’s tongue and connected to a Masimo pulse co-oximeter to determine ORI values. An arterial catheter was inserted into an auricular artery. After ORI signal stabilization, the value was noted and PaO2 determined by blood gas analysis. The Pearson correlation coefficient was used to assess the relationship between ORI and PaO2 for oxygen tension 150 and 200 mmHg (20.0 and 26.6 kPa) with the highest sensitivity and specificity. Results A total of 106 paired measurements were collected. A mild positive correlation was observed between ORI and PaO2 for values 0.0, > 0.1 and > 0.3 indicated a PaO2 > 100, > 150 and > 200 mmHg (13.3, 20.0 and 26.6 kPa) with negative predictive values > 94%. Conclusions and clinical relevance ORI may provide a noninvasive indication of PaO2 > 100, > 150 and > 200 mmHg (13.3, 20.0 and 26.6 kPa) in anaesthetized donkeys with an F i O2 > 0.95, although it does not replace blood gas analysis for assessment of oxygenation.

Objective To evaluate cardiopulmonary and recovery characteristics of horses administered total intravenous anesthesia (TIVA) with xylazine and ketamine combined with midazolam or propofol. Study design Randomized crossover study. Animals A group of eight adult horses, aged 7–22 years, weighing 493–740 kg. Methods Horses were administered xylazine (1 mg kg−1) intravenously (IV), and anesthesia was induced with ketamine (2.2 mg kg−1) IV. Anesthesia was maintained for 45 minutes via IV infusion of xylazine (0.016 mg kg−1 minute−1) and ketamine (0.03 mg kg−1 minute−1) combined with midazolam at 0.002 mg kg−1 minute−1 (MKX), propofol at 0.05 mg kg−1 minute−1 (PKXlow) or propofol at 0.1 mg kg−1 minute−1 (PKXhigh). Additional ketamine was administered if a horse moved spontaneously. Cardiopulmonary variables, blood gases, lactate concentration, packed cell volume and total solids were recorded before sedation (baseline), at 10, 20, 30 and 45 minutes during TIVA and 10 minutes after standing. Recovery variables and quantitative recovery scores were compared. Significance was set at p Results Additional ketamine was required for 50% of MKX horses. Systolic arterial pressure was elevated in MKX at 20 minutes compared with baseline (p = 0.043), at 10 and 20 minutes compared with PKXhigh (p = 0.007, p = 0.024) and at 20 and 30 minutes compared with PKXlow (p = 0.009, p = 0.02). MKX horses (5/8) were hypertensive compared with PKXlow (1/8; p = 0.017). All horses became hypoxemic (PaO2 ≤80 mmHg; 10.7 kPa) during TIVA. Recovery variables did not differ among treatments. Conclusions and clinical relevance PKXlow and PKXhigh had similar cardiopulmonary and recovery performance compared with MKX. PKX combinations provided superior quality of anesthesia to that of MKX. A combination of propofol, ketamine and xylazine administered as TIVA can be used in horses to provide anesthesia for short procedures. Supplemental oxygen is recommended.

Objective To compare the induction and recovery characteristics and selected cardiopulmonary variables of midazolam–alfaxalone or midazolam–ketamine in donkeys sedated with xylazine. Study design Randomized, blinded, crossover experimental trial. Animals A group of seven adult male castrated donkeys weighing 164 ± 14 kg. Methods Donkeys were randomly administered midazolam (0.05 mg kg −1 ) and alfaxalone (1 mg kg −1 ) or midazolam (0.05 mg kg −1 ) and ketamine (2.2 mg kg −1 ) intravenously following sedation with xylazine, with ≥ 7 days between treatments. Donkeys were not endotracheally intubated and breathed room air. Time to lateral recumbency, first movement, sternal recumbency and standing were recorded. Induction and recovery were assigned scores between 1 (very poor) and 5 (excellent). Heart rate (HR), respiratory rate ( f R ), invasive arterial blood pressures and arterial blood gases were measured before induction and every 5 minutes following induction until first movement. Results Time to lateral recumbency (mean ± standard deviation) was shorter after alfaxalone (29 ± 10 seconds) compared with ketamine (51 ± 9 seconds; p = 0.01). Time to first movement was the same between treatments (27 versus 23 minutes). Time to standing was longer with alfaxalone (58 ± 15 minutes) compared with ketamine (33 ± 8 minutes; p = 0.01). Recovery score [median (range)] was of lower quality with alfaxalone [3 (2–5)] compared with ketamine [5 (3–5); p = 0.03]. There were no differences in HR, f R or arterial pressures between treatments. No clinically important differences in blood gases were identified between treatments. Five of seven donkeys administered alfaxalone became hypoxemic (PaO 2 p = 0.13). Conclusions and clinical relevance Both midazolam–alfaxalone and midazolam–ketamine produced acceptable anesthetic induction and recovery in donkeys after xylazine sedation. Hypoxemia occurred with both treatments.

Objective To compare the effects of MK-467 during isoflurane anaesthesia combined with xylazine or dexmedetomidine on global and gastrointestinal perfusion parameters. Study design Prospective, randomized experimental trial. Animals A total of 15 warmblood horses. Methods Horses were divided into two groups for administration of either dexmedetomidine (D) or xylazine (X) for premedication (D: 3.5 μg kg−1; X: 0.5 mg kg−1) and as constant rate infusion during isoflurane anaesthesia (D: 7 μg kg−1 hour−1; X: 1 mg kg−1 hour−1). During anaesthesia, heart rate, mean arterial blood pressure (MAP), systemic vascular resistance index (SVRI) and cardiac index (CI) were measured. Microperfusion of the colon, jejunum and stomach was measured using laser Doppler flowmetry. After 2 hours of stabilization, MK-467 (250 μg kg−1) was administered, and measurements were continued for another 90 minutes. For statistical analysis, the permutation test and Wilcoxon rank-sum test were used (p Results There were no differences in baseline measurements between groups. The MK-467 bolus resulted in a significant decrease in MAP (D: –58%; X: –48%) and SVRI (D: –68%; X: –65%) lasting longer in group D (90 minutes) compared to group X (60 minutes). While CI increased (D: +31%; X: +35%), microperfusion was reduced in the colon (D: –44%; X: –34%), jejunum (D: –26%; X: –33%) and stomach (D: –37%; X: –35%). Conclusions and clinical relevance Alpha-2-agonist induced vasoconstriction was reversed by the MK-467 dose used, resulting in hypotension and rise in CI. Gastrointestinal microperfusion decreased, probably as a result of insufficient perfusion pressure. An infusion rate for MK-467 as well as an ideal agonist/antagonist ratio should be determined.

Objective To investigate the sedative effects in dogs of tiletamine–zolazepam–acepromazine (TZA) or ketamine–flunitrazepam (KF) administered orally and to evaluate the effectiveness of encapsulated TZA for capturing free-roaming dogs. Study design Experimental study followed by a field trial. Animals Six research dogs and 27 free-roaming dogs. Methods In a pilot study, six research dogs were administered liquid TZA (20 mg kg−1 tiletamine–zolazepam and 2 mg kg−1 acepromazine) or liquid KF (50 mg kg−1 ketamine and 2 mg kg−1 flunitrazepam) orally: treatment 1, forcefully squirting liquid medication into the mouth; treatment 2, encapsulating liquid medication for administration in canned food; treatment 3, administering liquid medication mixed with gravy. Sedation was scored. A follow-up field trial attempted capture of 27 free-roaming dogs. Results In the pilot study, the median time (range) to lateral recumbency (% dogs) after TZA administration was: treatment 1, 47.5 (35–80) minutes (67%); treatment 2, 30 (15–65) minutes (83%); and treatment 3, 75 (45–110) minutes (100%). No dogs in KF treatment 2 or 3 achieved lateral recumbency. Based on these results, 20 free-roaming dogs were offered encapsulated TZA in canned food: TZ (20 mg kg−1) and acepromazine (2 mg kg−1). Of these, no further drugs to four dogs (one dog captured), 10 dogs were administered a second dose within 30 minutes (five dogs captured) and six dogs were administered TZ (5 mg kg−1) and xylazine (1.1–2.2 mg kg−1) intramuscularly by blow dart (six dogs captured). Seven dogs were initially offered twice the TZA dose (five dogs captured). In total, 63% free-roaming dogs were captured after administration of encapsulated TZA in canned food. Conclusions and clinical relevance Oral administration of encapsulated TZA in canned dog food can aid in the capture of free-roaming dogs, but additional drugs may be required. The sedation onset time and medication palatability influenced the capture rate.

To measure intraocular pressure (IOP) in horses during hoisting after induction of anesthesia.Prospective nonrandomized clinical study.Eighteen healthy adult horses aged [mean±standard deviation (SD)] 10±4.2 years and weighing 491±110 kg anesthetized for elective procedures.IOP was measured in the superior eye of each horse based on planned recumbency after induction of anesthesia. Measurements were taken directly after premedication with xylazine or detomidine with butorphanol, after induction with diazepam-ketamine, after intubation, when suspended by the hoist and on the operating table. During hoisting, the head was supported and the eye-heart height was measured to account for variations in head positioning among patients. IOPs were compared across time points using repeated-measures analysis of variance. Regression was used to compare IOP outcome with potential cofactors.Compared with measurements after premedication (17.5±2.5 mmHg) (mean±SD), hoisting significantly increased IOP (32.4±15.3 mmHg) (p0.01). The highest recorded IOP in the hoist was 80.0 (range, 16.0-80.0) mmHg. The difference in IOP between premedication and hoisting was 15.0±16.2 (range, -1.0 to 68.0) mmHg. Body weight had a significant effect on absolute IOP and change in IOP in the hoist (p0.01).Hoist IOP was significantly higher than post-premedication IOP with heavier horses having higher hoist IOPs and greater increases in IOP. The clinician should take this relationship into account when anesthetizing and hoisting larger horses where an increase in IOP could be detrimental.

Objective To record the cardiopulmonary effects of pleural CO 2 positive pressure insufflation in anesthetized horses. Study design Prospective study. Animals Seven horses (mean ± standard deviation, 530.9 ± 68.1 kg) undergoing terminal surgery. Methods Horses were sedated with xylazine. Anesthesia was induced with ketamine–propofol and maintained with isoflurane, positive pressure ventilation, detomidine infusion, and butorphanol with the horses in dorsal recumbency. Baseline measurements were cardiac output, heart rate, pulmonary and systemic arterial and right atrial blood pressures, body temperature, expired and inspired gas concentrations, and arterial and mixed venous blood gases, electrolytes, glucose, and lactate concentrations. An 18 gauge 6.6 cm needle was inserted into the right pleural cavity midway between the sternum and dorsal midline in the sixth or seventh intercostal space for pleural pressure (PP) measurement. A 14 gauge 18 cm needle placed 5 cm below the previous needle allowed CO 2 insufflation into the pleural cavity. All measurements were repeated after: needle insertion, at 2, 5, and 8 mmHg PPs, and after pleural gas removal (GR). Data were compared with baseline using one-way analysis of variance with repeated measures. p Results Actual PPs were within 1.1 mmHg of the targeted PP. Pulmonary systolic and mean arterial pressures, alveolar dead space to tidal volume ratio, and isoflurane requirements increased at 8 mmHg PP and GR. Cardiac index decreased at 5 mmHg PP. Stroke index decreased at 2 mmHg PP to GR. PaO 2 decreased at 5 mmHg PP to GR. PaCO 2 increased at 8 mmHg PP and GR. Oxygen delivery decreased at 5 and 8 mmHg PP. Intrapulmonary shunt fraction and lactate concentration increased with GR. Conclusions and clinical relevance: Severe adverse cardiopulmonary effects arise from CO 2 positive pressure insufflation into the right hemithorax in dorsally recumbent isoflurane-anesthetized horses. PP should be ≤2 mmHg.

Objective To compare postanesthetic xylazine and dexmedetomidine on recovery characteristics from sevoflurane anesthesia in horses. Study design Randomized, crossover study. Animals Six geldings, mean ± standard deviation (SD) (range), 17 ± 4 (11–24) years and 527 ± 80 (420–660) kg. Methods Horses were anesthetized with sevoflurane for 60 minutes under standardized conditions for a regional limb perfusion study. In recovery, horses were administered either xylazine (200 μg kg −1 ) or dexmedetomidine (0.875 μg kg −1 ) intravenously. Recoveries were unassisted and were video-recorded for later evaluation of recovery events and quality by two individuals unaware of treatment allocation. Recovery quality was assessed using a 100 mm visual analog scale (VAS) (0 = poor recovery, 100 = excellent recovery), the Edinburgh Scoring System (ESS) (0–100; 100 = excellent recovery) and the mean attempt interval (MAI) (longer = better). Data are mean ± SD. Results All recovery quality assessments (xylazine and dexmedetomidine, respectively: VAS: 71 ± 21 mm, 84 ± 13 mm; ESS: 65 ± 22, 67 ± 30; MAI: 52 ± 24 minutes, 60 ± 32 minutes) and events (first limb movement: 37 ± 8 minutes, 42 ± 10 minutes; first attempt to lift head: 44 ± 12 minutes, 48 ± 9 minutes; first attempt to sternal posture: 57 ± 28 minutes, 50 ± 7 minutes; number of head bangs: 2.0 ± 3.0, 0.5 ± 0.5; time to first attempt to stand: 72 ± 6 minutes, 78 ± 13 minutes; time to standing: 79 ± 14 minutes, 84 ± 13 minutes) did not differ significantly between treatments ( p > 0.05). Conclusions and clinical relevance Recovery characteristics did not differ significantly between postanesthetic xylazine and dexmedetomidine following 1 hour of sevoflurane anesthesia in horses in this study. Further evaluations in more horses and in younger horses are required to confirm these results.

Objective To investigate whether an intravenous (IV) lidocaine bolus in calves premedicated with xylazine-butorphanol reduces the amount of ketamine required to allow endotracheal intubation. Study design Randomized, prospective clinical study. Animals In total, 41 calves scheduled for elective umbilical surgery. Methods Calves were randomly assigned to one of two groups (L: lidocaine or S: saline). The calves were administered xylazine (0.07 mg kg−1) and butorphanol (0.1 mg kg−1) intramuscularly and 10 minutes later lidocaine (2 mg kg−1; group L) or saline (group S) IV over 1 minute. After 2 minutes, ketamine (2.5 mg kg−1) was injected IV. If the depth of anaesthesia was insufficient for intubation, additional ketamine (1 mg kg−1) was administered every minute until intubation was successful. The amount of ketamine required for intubation, respiratory rate, pulse rate, arterial pressures, the depth of sedation and conditions of endotracheal intubation after induction of anaesthesia were compared between the two groups. Results The calves in group L were sedated more deeply than those in group S; however, neither the median (range) amount of ketamine required for intubation, 3.5 (2.5–4.5) mg kg−1 and 3.5 (2.5–3.5) mg kg−1, respectively, nor the induction quality differed significantly between the groups. Conclusion and clinical relevance A bolus of lidocaine (2 mg kg−1) administered 10 minutes after xylazine-butorphanol in calves deepened the degree of sedation but did not decrease the requirement of ketamine for endotracheal intubation. No adverse effects were recorded in the physiological variables measured.

Objective To investigate the effects of intravenous (IV) administration of terbutaline on PaO2, PaCO2, pH, heart rate (HR) and arterial pressures in healthy, laterally recumbent horses breathing ambient air under total intravenous anesthesia (TIVA). Study design Prospective experimental study. Animals Eight healthy adult horses were enrolled. Six horses, four mares and two geldings weighing 433-624 kg, completed the study. Methods Horses were sedated with xylazine (1.0 mg kg−1) IV for placement of arterial and venous catheters. Anesthesia was induced with midazolam (0.1 mg kg−1) and ketamine (2.2 mg kg−1) IV and maintained with an IV infusion of guaifenesin (50 mg mL−1), ketamine (2 mg mL−1) and xylazine (0.5 mg mL−1) at 1.9 ± 0.3 mL kg−1 hour−1. Horses were in left lateral recumbency and breathed air spontaneously. Arterial blood was collected for pH and blood gas analysis during xylazine sedation, 15 minutes after induction of anesthesia, immediately before and 5, 15 and 30 minutes after administration of terbutaline (2 μg kg−1), and when the horse was standing after recovery from anesthesia. HR, systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded at 5 minute intervals during anesthesia. Normal data were analyzed with anova and non-normal data were analyzed with a Friedman test with a p Results The mean PaO2 decreased from baseline to Conclusions and clinical relevance Terbutaline (2 μg kg−1) IV did not improve PaO2 and was associated with adverse cardiovascular effects during TIVA in healthy, laterally recumbent horses breathing air.

Objective To compare oxygenation and ventilation in white-tailed deer (Odocoileus virginianus) anesthetized with two treatments with and without oxygen supplementation. Study design Randomized, blinded, crossover study. Animals A total of eight healthy adult white-tailed deer weighing 49–62 kg. Methods Each deer was anesthetized twice intramuscularly: 1) treatment XK, xylazine (2 mg kg–1) and ketamine (6 mg kg–1) and 2) treatment XTZ, xylazine (2 mg kg–1) and tiletamine–zolazepam (4 mg kg–1). With the deer in sternal position, arterial and venous blood was collected before and at 30 minutes during administration of oxygen at 1 L minute–1 through a face mask. PaO2 and heart rate (HR) were compared using two-way repeated measures anova . pH, PaCO2 and lactate concentration were analyzed using mixed-effects linear models, p Results When breathing air, PaO2 was Conclusions and clinical relevance Treatments XK and XTZ resulted in hypoxemia, which responded to oxygen supplementation. Both treatments are suitable for immobilization of white-tailed deer under the study circumstances.

Objective To evaluate allometric scaling for ketamine–xylazine (KX) anesthesia in wild felids using domestic cats for reference. Study design Prospective single-phase non-blinded study. Animals Six domestic cats and 13 wild felids (five Leopardus pardalis , five Puma concolor , one Panthera onca and two Panthera leo ). Methods Six domestic cats (4.1 ± 0.8 kg, REF1) were anesthetized by intramuscular administration of ketamine (15 mg kg -1 ) and xylazine (1 mg kg -1 ). Wild cats were divided into three groups based on body weight: 12.9 ± 2.4 kg (G1; n = 7), 43.0 ± 15.7 kg (G2; n = 4) and 126.0 ± 7.8 kg (G3; n = 2). Ketamine and xylazine doses were calculated based on allometric scaling of the basal metabolic rate (BMR = 70 × body mass 0.75 ). Afterwards, the six domestic cats were administered mean KX doses calculated for G1 and G2 (REF2). The heart rate, systolic arterial pressure, respiratory frequency, pH, the venous partial pressure of carbon dioxide, bicarbonate and lactate concentrations were recorded for up to 60 minutes. Results Additional doses were required in 12 out of the 13 wild cats. Anesthesia was not achieved in G3. Latency periods in wild felids were longer than REF1 and REF2. Anesthesia duration in REF1 was longer than that in the other groups. Recovery from anesthesia in REF1 and REF2 was longer than G1 and G2. Physiological variables remained within the range limits for the species. G1 baseline lactate concentration was higher than in the other groups. Conclusion and clinical relevance KX anesthesia established by allometric scaling of BMR from doses administered to domestic cats did not predict reliable anesthetic doses for wild cats. Dose rates calculated with this method must not be applied to these species.

Objective To design an effective intravenous (IV) anaesthetic combination for field use in mules. Study design Descriptive study. Animals Six healthy adult mules. Methods Xylazine 1.3 mg kg −1 was administered IV and the quality of sedation was recorded. Anaesthesia was induced with 0.03 mg kg −1 diazepam and 2.2 mg kg −1 ketamine IV. Times to sternal recumbency, lateral recumbency and standing were recorded. Heart rate (HR), respiratory rate ( f R ), rectal temperature and haematological parameters were recorded at baseline and at 5, 15 and 45 minutes post-administration. Additionally, levels of antinociception according to responses to a pin prick test, and the quality of muscle relaxation and recovery were scored. Results Times (mean ± standard deviation) to sternal and lateral recumbency were 1.3 ± 1.3 minutes and 1.8 ± 1.3 minutes, respectively, with hypertonicity of the pelvic limbs. Standing ataxia and normal gait were seen at 25.5 ± 19.0 minutes and 32.8 ± 7.9 minutes, respectively. Five minutes after induction of anaesthesia, the quality of antinociception was judged to be good to excellent (0 ± 1 on a scale of 0–3), muscle relaxation of the jaw incomplete (2 ± 1 on a scale of 1–4) and quality of recovery was very good to excellent (2 ± 1 on a scale of 1–5). The duration of anaesthesia was only 15.3 ± 1.6 minutes. Significant changes were observed only in HR at 15 minutes and f R at 5 minutes. Changes in rectal temperature and haematological parameters following anaesthesia were non-significant. Conclusions and clinical relevance The combination of xylazine–diazepam–ketamine provides effective short-term anaesthesia in mules under field conditions.

Made available in DSpace on 2015-10-21T13:08:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-01 ObjectiveThis study aimed to evaluate the benefit and specifically the feasibility of using ultrasound in ophthalmologic periconal block, and the occurrence of complications.Study designProspective experimental study.AnimalsTen healthy New Zealand White rabbits (6-8months of age), weighing 2.0-3.5kg.MethodsRabbits were anesthetized by intramuscular injection of acepromazine (1mgkg(-1)), ketamine (30mgkg(-1)) and xylazine (3mgkg(-1)). Ultrasound-assisted periconal block with lidocaine was performed on 18 eyes. Intraocular pressure was measured by applanation tonometry whereas corneal sensitivity was assessed using an esthesiometer, before and after each periconal anesthesia.ResultsIn all 18 eyes, it was possible to adequately visualize the needle shaft within the periconal space, as well as muscular cone, optic nerve and local anesthetic solution spread. Lidocaine 2% without epinephrine (0.790.19mL) was injected into the periconal space. There was no statistical difference between the intraocular pressure (meanSD) measured before (10.9 +/- 2.9mmHg) and after (11.9 +/- 3.8mmHg) the periconal anesthesia (p=0.38). The effectiveness of the ultrasound-assisted technique was shown according to the values for corneal sensitivity, assessed before and after periconal anesthesia (p

Objective Previous studies showed an influence of xylazine on the LiDCO sensor in vitro and in standing horses, but did not prove that this interaction caused error in LiDCO measurements. Therefore, agreement of cardiac output (CO) measurements by LiDCO and bolus-thermodilution (BTD) was determined in horses receiving xylazine infusions. Study design Prospective, experimental study. Animals Eight Warmblood horses. Methods All horses were premedicated with xylazine. Anaesthesia was induced with midazolam and ketamine and was maintained with isoflurane in oxygen. During six hours of anaesthesia CO measurements and blood samples were taken before, during and after a 60 minute period of xylazine infusion. Pairs of LiDCO and bolus thermo-dilution (BTD) measurements of CO were performed. Sensor voltages exposed to blood and saline were measured before, during and after xylazine infusion and compared using Bland-Altman method of agreement with corrections for repeated measures. Results The CO values (mean ± SD) before xylazine were 34.8 ± 7.3 and 36.4 ± 8.1 L minute−1 for BTD and LiDCO, respectively. After starting the xylazine infusion, the CO values for BTD decreased to 27.5 ± 6.1 L minute−1 whereas CO values measured by LiDCO increased to 54.7 ± 18.4 L minute−1. One hour after discontinuing xylazine infusion, CO values were 33 ± 6.7 and 36.5 ±11.9 L minute−1 for BTD and LiDCO, respectively. The difference between saline and blood exposed sensor voltages decreased during xylazine infusion and these differences were positive numbers before but negative during the infusion. There were correlations between xylazine plasma concentrations, CO differences and sensor voltage differences (saline – blood). Conclusions and clinical relevance This study proved that xylazine infusion caused concentration dependent bias in LiDCO measurements leading to an overestimation of readings. Sensor voltage differences (saline – blood) may become valuable clinical tool to predict drug-sensor interactions.

Objective To establish an accurate anaesthetic dose for chemical restraint of African mole-rats using ketamine and xylazine. Study design Prospective nonrandomized laboratory study. Animals Sixteen adult Ansell’s mole-rats ( Fukomys anselli ) and eight giant mole-rats ( F. mechowii ). Methods Fukomys anselli of different ages, sexes and reproductive status were systematically anaesthetized starting with an intramuscular injection of ketamine (2.5 mg kg −1 ) and increasing the doses in steps of 0.5 mg kg −1 until loss of the righting reflex (LRR) was observed. Xylazine was added to a constant dose of ketamine, starting at 0.5 mg kg −1 that was increased by 0.5 mg kg −1 in further trials. Once an effective combination was established and evaluated in F. anselli , it was also tested in F. mechowii . Heart and respiratory rates and rectal temperatures were measured during anaesthesia. anova for repeated measures and Student’s t-test were used to compare means. Results Chemical restraint was accomplished at a dose of 6 mg kg −1 ketamine combined with 2.5 mg kg −1 xylazine. LRR lasted on average mean 56 ± SD 19 minutes ( F. anselli ) and 140 ± 41 minutes ( F. mechowii ). Loss of pedal withdrawal reflex (LPR) lasted for 20 ± 15 minutes ( F. anselli ) and for 29 ± 2 minutes ( F. mechowii ), respectively. All animals recovered satisfactorily. Heart and respiratory rates were stable during anaesthesia, but rectal temperature fell significantly in F. mechowii after losing the righting reflex (LRR) from T1 (32.6 ± 0.6 °C) to T3 (30.4 ± 0.9 °C). Conclusions and Clinical relevance African mole-rats (Bathyergidae) live in closed burrow systems under particular conditions (hypercapnia, hypoxia, stable temperature, humidity, darkness) and show several physiological adaptations. Injectable anaesthetics in the dose rates used in other rodents are not appropriate for use in these subterranean species. Here, a reliable protocol for chemical restraint is provided.

Objective To examine the cardiopulmonary effects of two anesthetic protocols for dorsally recumbent horses undergoing carpal arthroscopy. Study design Prospective, randomized, crossover study. Animals Six horses weighing 488.3 ± 29.1 kg. Methods Horses were sedated with intravenous (IV) xylazine and pulmonary artery balloon and right atrial catheters inserted. More xylazine was administered prior to anesthetic induction with ketamine and propofol IV. Anesthesia was maintained for 60 minutes (or until surgery was complete) using either propofol IV infusion or isoflurane to effect. All horses were administered dexmedetomidine and ketamine infusions IV, and IV butorphanol. The endotracheal tube was attached to a large animal circle system and the lungs were ventilated with oxygen to maintain end-tidal CO 2 40 ± 5 mmHg. Measurements of cardiac output, heart rate, pulmonary arterial and right atrial pressures, and body temperature were made under xylazine sedation. These, arterial and venous blood gas analyses were repeated 10, 30 and 60 minutes after induction. Systemic arterial blood pressures, expired and inspired gas concentrations were measured at 10, 20, 30, 40, 50 and 60 minutes after induction. Horses were recovered from anesthesia with IV romifidine. Times to extubation, sternal recumbency and standing were recorded. Data were analyzed using one and two-way anova s for repeated measures and paired t -tests. Significance was taken at p =0.05. Results Pulmonary arterial and right atrial pressures, and body temperature decreased from pre-induction values in both groups. PaO 2 and arterial pH were lower in propofol-anesthetized horses compared to isoflurane-anesthetized horses. The lowest PaO 2 values (70–80 mmHg) occurred 10 minutes after induction in two propofol-anesthetized horses. Cardiac output decreased in isoflurane-anesthetized horses 10 minutes after induction. End-tidal isoflurane concentration ranged 0.5%–1.3%. Conclusion and clinical relevance Both anesthetic protocols were suitable for arthroscopy. Administration of oxygen and ability to ventilate lungs is necessary for propofol-based anesthesia.

To evaluate and compare the analgesic effects of a combination of lidocaine and xylazine to lidocaine or xylazine administered alone for epidural anesthesia in Egyptian water buffalo (Bubalus bubalis).Prospective, randomized, 'blinded', crossover experimental study.A total of 12 female Egyptian water buffalo.Buffalo were randomly assigned to one of three epidural treatments administered through the sacrococcygeal joint: a local anesthetic (2% lidocaine, 0.22 mg kgCaudal epidural anesthesia was easily performed, and all three treatments produced local anesthesia of the tail and perineal structures of standing buffalo. Onset of epidural anesthesia was faster (p 0.05) with lidocaine (3.4 ± 0.9 minutes) than with xylazine (9.1 ± 1.1 minutes) or lidocaine-xylazine (6.4 ± 1.1 minutes). The maximal effect of epidural anesthesia was reached faster (p 0.05) with lidocaine (5.9 ± 0.64 minutes) than xylazine (14.4 ± 1.1 minutes) or lidocaine-xylazine (12.9 ± 0.64 minutes). The duration of epidural anesthesia was longer (p 0.05) with lidocaine-xylazine (145.8 ± 3.3 minutes) than either lidocaine (118.4 ± 2.7 minutes) or xylazine (102.1 ± 3.7 minutes) administered alone. None of the treatments produced ataxia.Caudal epidural anesthesia was easily performed in Egyptian water buffalo by administering a local anesthetic, an alpha-2-adrenergic agonist or a combination of both drugs through the sacrococcygeal joint. Administering a combination of lidocaine and xylazine provided a longer duration of anesthesia than either drug used alone. Epidural xylazine provided a useful level of systemic sedation without ataxia.

To compare the topographic modifications and tactile sensitivity of the pharynx and larynx after administration of four sedative and analgesic protocols in standing horses.Experimental, observer-blinded, crossover study.Eight healthy mares.Five protocols were evaluated: 1) xylazine and butorphanol administered intravenously (IV); 2) detomidine and butorphanol administered IV; 3) xylazine administered IV and lidocaine topically; 4) detomidine administered IV and lidocaine topically and 5) no analgesia or sedation (control). Quality of sedation, head height and sudden head movements were recorded. The degree of arytenoid cartilage displacement, the degree of pharyngeal collapse and the occurrence of soft palate displacement were scored using standardized scales. Tactile sensitivity was tested on 10 different pharyngeal and laryngeal regions using an atraumatic transendoscopic probe. Statistical analysis was performed using linear or generalized mixed-effects models.Head height was significantly decreased in protocols with xylazine (p = 0.002). Head movements were significantly increased in protocols with butorphanol (p = 0.0001). No changes in abduction grade or degree of soft palate displacement were observed between all sedative protocols and the control group. Pharyngeal collapse was significantly more frequent in protocols with lidocaine (p 0.001) or xylazine (p = 0.017). For the pharyngeal regions, no tactile sensitivity difference was observed between the control and treatment protocols. All treatment protocols led to greater desensitization of all the laryngeal regions compared with the control protocol.All the protocols provided adequate sedation and analgesia for the manipulation of the larynx and pharynx but significant differences were noted. Xylazine produces a more profound sedation compared with detomidine, but can induce dorsal pharyngeal collapse. Lidocaine caused pharyngeal collapse and its use should be limited to the target area. Butorphanol can be added to improve analgesia in the other regions but frequent head jerking can be expected.

Studies evaluating the effects of dobutamine in horses do not consistently report increases in cardiac output despite increases in arterial blood pressure. The concurrent administration of the α2 agonist clonidine, in people, inhibited the chronotropic effects of dobutamine and increased left ventricular stroke work (Zimpfer et al. 1982). Our study was performed to determine if pre-medication with an α2 agonist affects the response to dobutamine in anaesthetized horses. Eleven horses were anaesthetized on four separate occasions for one of four randomly assigned treatments; (I) no xylazine, no dobutamine (II) xylazine, no dobutamine (III) no xylazine, dobutamine, and (IV) xylazine, dobutamine. Horses received 0.02 mg kg−1 of butorphanol IV 10 minutes prior to anesthetic induction. Two minutes prior to induction, groups II and IV received 0.5 mg kg−1 of IV xylazine. Anaesthesia was induced with 6–7 mg kg−1 of thiopental and maintained with halothane. End-tidal halothane concentrations were maintained between 1.1 and 1.2% in groups I and III, and 0.9–1.0% for groups II and IV. Heart rate, cardiac output, right atrial pressure, and systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressure were recorded 30 minutes after beginning halothane anaesthesia (T10). Cardiac output was estimated using Lithium dilution (Linton et al. 2000). Baseline measurements were repeated twice, at 5-minute intervals (T5 and T0). At time 0 (T0), an IV infusion of either saline (100 mL hour−1) or dobutamine (0.001 mg kg−1 minute−1) was started and data recorded at 5-minute intervals for 30 minutes (T5 – T30). Stroke volume and systemic vascular resistance (SVR) were calculated. Data were analysed using repeated measures anova (p

Alpha-2 agonists cause transient dose-related increase in urine flow in normal horses. Although important clinically, effects of these drugs in dehydrated animals are not known. The purpose of this study was to describe the influence of xylazine (XYL) and detomidine (DET) on urine flow in mares deprived of food and water for 24 hours. Six clinically normal mares [12.5 ± 3.3 (mean ± SE) years] weighing 471 ± 23 kg were each studied four times; each study was separated by at least 7 days. The morning following fasting, the urinary bladder was catheterized (Foley) and emptied. Urine was then collected for 2 hours and a composite urine sample along with a sample of jugular venous blood provided baseline values. Shortly after emptying the bladder, saline, 0.5 or 1.0 mg kg−1 XYL or 0.03 mg kg−1 DET was injected IV (treatment randomly assigned) and urine and blood samples obtained over the next 2 hours. Data were analyzed by RM anova followed by Dunnett's test for pairwise comparisons p

The study of free-ranging, endangered species almost always requires immobilization for collection of biological samples and radiotransmitter placement. Although monitoring assists in assuring safe immobilization, scant information is available regarding physiological monitoring of tapirs. This study was designed to test the effectiveness of noninvasive, oscillometric arterial blood pressure monitoring (NIBP) in wild captured tapirs. Six adult Baird's tapirs (Tapirus bairdii) estimated to weigh 235 ± 23.6 kg (mean ± SEM) were attracted to a capture area using ripe bananas as bait. Animals were darted with a mixture of 50 mg butorphanol (0.23 ± 0.03 mg kg−1) and 100 mg xylazine (0.46 ± 0.07 mg kg−1) using a CO2 pistol. Propofol (100 µg kg−1 minute−1 IV, n = 2; 200 µg kg−1 minute−1 IV, n = 2) or ketamine (0.35 ± 0.05 mg kg−1 IV, n = 1) were delivered to maintain immobilization in all but one case. A commercial blood pressure cuff (cuff bladder width to limb circumference ratio 0.399 ± 0.01) was applied to the thoracic limb, and a 20-ga, 3.8 cm catheter was placed in the facial artery on the nondependent side of the laterally recumbent tapir. A laser line-level and careful positioning were used to assure the cuff center and pressure transducer were at the same level, and were at the approximated level of the right atrium. Systolic (SAP), diastolic (DAP) and mean arterial pressure (MAP) were recorded simultaneously (at end cuff decompression). The lower limits of the range of invasive arterial blood pressure (IBP) were 94 ± 18 mm Hg, 58 ± 18 mm Hg and 74 ± 17 mm Hg for SAP, DAP and MAP, respectively. The upper limits of the range of IBP were 114 ± 13 mm Hg, 74 ± 11 mm Hg and 87 ± 13 mm Hg for SAP, DAP, and MAP, respectively. Mean heart rate was 52 ± 9 beats minute−1. To assess agreement and correlation between IBP and NIBP methods of measurement, both correlation analysis and Bland-Altman analysis of agreement (bias and limits of agreement) were performed. Pearson's correlation coefficients were 0.858, 0.801 and 0.912 for SAP, DAP and MAP, respectively. Bias (mean differences) were − 9 mm Hg, − 12 mm Hg and − 7 mm Hg for SAP, DAP and MAP, respectively. The lower limits of agreement were − 21 mm Hg, − 29 mm Hg and − 24 mm Hg for SAP, DAP and MAP, respectively. The upper limits of agreement were 3 mm Hg, 4 mm Hg and 9 mm Hg for SAP, DAP and MAP, respectively. Both correlation and agreement analysis indicated noninvasive oscillometric blood pressure measurement is satisfactory for field blood pressure monitoring, but tend to read falsely low using the described technique.

Horses airlifted by helicopter must be cooperative, able to support their own weight plus the weight of the rescue sling, nonreactive to helicopter approach, hovering, lift-off, and transport; and able to support their own weight without significant ataxia during delivery to safe ground. The flooding that occurs in Louisiana has given us the opportunity to be involved in airlift rescue of eight horses stranded by high water. In our experience, the effective titration of sedatives is best accomplished through an IV catheter placed in one of the jugular veins rather than by repeated IV injections. Prior to the catheter placement, we sedate the horses with either xylazine (0.4–0.5 mg kg−1 IV) or detomidine (8–10 µg kg−1 IV). The process of airlifting can be divided into four phases: (1) attachment of lift sling; (2) helicopter approach and hover during attachment of the sling to the aircraft; (3) lift and transport; and (4) delivery to safe zone. The IV administration of an additional 0.4–0.5 mg kg−1 of xylazine immediately prior to placing the horse in the lift sling produces an appropriate level of sedation without excessive ataxia. With the sling in place and the horse blindfolded, the helicopter is called. As the helicopter approaches, another 0.4–0.5 mg kg−1 xylazine administered. The IV is generally sufficient to prevent reaction to the noise and wind associated with the hovering of the helicopter. After the lift sling is connected to the helicopter, a final dose of xylazine (0.25 mg kg−1 IV) has proven effective in reducing reaction to lift and transport. This sedation protocol has proven effective for airlifts of approximately 5–10-minutes duration. Thus sedated, horses are able to support their weight without excessive ataxia when delivered to their destination. Xylazine appears to be more effective than detomidine because of its shorter latency of onset and duration of action.

The purpose of this study was to evaluate the cardiopulmonary effects of anesthetic induction with diazepam/ketamine or xylazine/ketamine with subsequent maintenance of anesthesia using isoflurane in foals undergoing abdominal surgery. Seventeen foals underwent laparotomy at 7–10 days of age and a laparoscopy 7–10 days later. Foals were randomly assigned to receive xylazine (0.8 mg kg−1)/ketamine (2 mg kg−1) (X/K)(n = 9) or diazepam (0.2 mg kg−1)/ketamine (2 mg kg−1) (D/K)(n = 8) for induction of anesthesia for both procedures. In all foals, anesthesia was maintained with isoflurane in oxygen with the inspired concentration adjusted to achieve adequate depth of anesthesia as assessed by an individual blinded to the treatments. IPPV was employed throughout using a tidal volume of 10 mL kg−1 adjusting the frequency to maintain eucapnia (PaCO2 35–45 mm Hg, 4.7–6.0 kPa). Cardiopulmonary variables were measured after induction of anesthesia prior to, during, and following surgery. To compare the measured cardiopulmonary variables between the two anesthetic regimes for both surgical procedures, results were analyzed using a three-way factorial anova for repeated measures (p

As a result of anatomic and physiologic differences, draft breeds may be at greater risk of developing anesthetic complications. The aim of the study was to evaluate and compare anesthetic management of draft (DR) and light (LT) horses. A case-matched retrospective study of 371 clinical case records of DR (124 cases) and LT (247 cases) horses presented for general anesthesia between 1991 and 1998 was performed. Data were tabulated and comparisons were made using Student's t-test (significance p

The purpose of this study was to characterize urine flow and biochemical parameters in horses given xylazine (XYL) and anesthetized with ketamine and isoflurane. Nine mares [9 ± 2 (mean ± SE) years; 492 ± 17 kg] were studied. They were anesthetized for 2 hours in support of a campus-approved, laboratory-based orthopedic study. The day prior to anesthesia, a venous blood sample was obtained for biochemical analysis from each unmedicated mare. The urinary bladder was catheterized and emptied, and urine collected over the next three hours to quantitate the pre-drug values. The next day the mares were similarly catheterized. After obtaining urine and venous blood samples, XYL (1.1 mg kg−1 IV) was administered. Anesthesia was induced 5 minutes later with ketamine (2.2 mg kg−1 IV) and diazepam (0.04 mg kg−1 IV) and maintained with isoflurane in O2. Lactated Ringer's solution (10 mL kg−1 hours−1) was administered IV and dobutamine infused as required to maintain mean arterial blood pressure between 70 and 80 mm Hg. Mechanical ventilation maintained PaCO2 between 48 and 52 mm Hg and PaO2 > 200 mm Hg. Blood and urine were collected at 30, 60, and 120 minutes during anesthesia, and at 1 hour postanesthesia. Data were analyzed with RM anova; with p

Five female and four male guinea pigs, 2.0 ± 0.5 months of age and weighing 702 ± 72 g, were used in a crossover design to compare sedative and anesthetic effects of IM injection (INJ) of tiletamine-zolazepam (10 mg kg−1) – ketamine (4 mg kg−1) – xylazine (5 mg kg−1) – butorphanol (0.1 mg kg−1) (TKXB-H), tiletamine-zolazepam (5 mg kg−1) – ketamine (2 mg kg−1) – xylazine (2.5 mg kg−1) – butorphanol (0.05 mg kg−1) (TKXB-L), and medetomidine (0.5 mg kg−1) – ketamine (20 mg kg−1) – butorphanol (0.2 mg kg−1) (MBK) combinations. Yohimbine (YOH), 2 mg kg−1 IM, YOH, 1 mg kg−1 IM, and atipamezole (ATI), 2.5 mg kg−1 IM, were used to reverse (REV) xylazine and medetomidine in three groups, respectively, at 100 minutes after INJ. Heart rate (HR), Doppler systolic blood pressures (BP) (neonatal size cuff), respiratory rate (RR), and SpO2 were measured at baseline and every 10 minutes after INJ and at 5 and 10 minutes following REV. Jaw tone, palpebral reflex, corneal reflex, toe pinch, skin pinch, ECG and body temperature were monitored every 10 minutes after INJ for 100 minutes. In addition, four female and three male guinea pigs from the original group were anesthetized with TKXB-H for castration and ovariohysterectomy. Cardiorespiratory functions were monitored during the surgery. Following surgery, YOH (2 mg kg−1 IM) was used to shorten recovery. anova for repeated measures and Tukey's honestly significant test were used for analysis (p

Treatment of bradycardia in horses has been historically ignored because of the motility depressant effects of nonselective antimuscarinics. This study evaluated the cardiopulmonary effects of a cardioselective (M2) muscarinic antagonist, methoctramine (MET), in anesthetized horses. In a previous in vitro study, we determined that supraphysiological doses of MET were necessary to inhibit acetylcholine-induced longitudinal jejunal smooth muscle contractions in this species. Six adult horses were allocated to two treatments in a randomized complete block design. Anesthesia was induced with xylazine/ketamine, and maintained with halothane (1% end-tidal) and a constant infusion of xylazine (1 mg kg−1 hour−1) under mechanical ventilation. Invasive hemodynamic variables were monitored at baseline (approximately 45 minutes after induction) and for 120 minutes after MET or saline (control) had been injected. MET was titrated at 10-minute intervals (10 µg kg−1 IV) until the heart rate (HR) increased at least 30% above the baseline, or a maximum cumulative dose of 30 µg kg−1 had been injected. A person blinded to the treatment evaluated recovery scores and monitored intestinal auscultation until 24 hours after the end of anesthesia using previously published methods. Cardiovascular parameters were analyzed by anova followed by a Dunnet's test, and nonparametrical data were analyzed by a Mann–Whitney U-test (p

Trap-neuter-return programs have become a popular nonlethal alternative for the control of feral cat populations. The anesthetic used is an integral component of these programs. This study evaluated the use of tiletamine–zolazepam–ketamine–xylazine (TKX) as an IM anesthetic combination for large-scale feral cat sterilization surgery. Between July 1996 and August 2000, a total of 7502 cats entered large-scale feral cat clinics operating at the Colleges of Veterinary Medicine at North Carolina State University and the University of Florida. Up to 12 surgeries were performed simultaneously and up to 200 cats were sterilized in a single day. Cats were not weighed prior to anesthetic injection owing to their feral nature, so the initial anesthetic dose was based on estimated body weight. Tiletamine–zolazepam–ketamine–xylazine was administered IM while cats remained in their traps. Each milliliter of TKX contained 50 mg tiletamine, 50 mg zolazepam, 80 mg ketamine, and 20 mg xylazine. The cats were monitored by observation and palpation for mucous membrane color, heart rate, and respiratory rate, but these values were not recorded. Fluids were not routinely administered but were given subcutaneously in cases of dehydration or excessive blood loss. Yohimbine (0.5 mg) was administered IV at the end of the procedure, and cats were returned to their traps to recover. Cat signalment, drug use, and mortality data were analyzed retrospectively (July 1996–December 1999) and prospectively (December 1999–August 2000). Of those cats with complete drug records, more than 75% received a single dose of TKX with a mean total dose of 0.27 ± 0.09 mL. The overall mortality rate was one in 289 cats (0.347%) and the death rate owing to unknown causes (potential anesthetic deaths) was one in 469 cats (0.213%). These results suggest that the use of TKX for large-scale feral cat sterilization clinics has several benefits, including small volume of administration, predictable anesthetic quality and duration, low cost, and low mortality in feral cats.

Objectives To evaluate the cardiorespiratory and biochemical effects of ketamine-propofol (KP) or guaifenesin-ketamine-xylazine (GKX) anesthesia in donkeys. Study design Prospective crossover trial. Animals Eight healthy, standard donkeys, aged 10 ± 5 years and weighing 153 ± 23 kg. Methods Donkeys were premedicated with 1.0 mg kg −1 of xylazine (IV) in both treatments. Eight donkeys were administered ketamine (1.5 mg kg −1 ) and propofol (0.5 mg kg −1 ) for induction, and anesthesia was maintained by constant rate infusion (CRI) of ketamine (0.05 mg kg −1 minute −1 ) and propofol (0.15 mg kg −1 minute −1 ) in the KP treatment. After 10 days, diazepam (0.05 mg kg −1 ) and ketamine (2.2 mg kg −1 ) were administered for induction, and anesthesia was maintained by a CRI (2.0 mL kg −1 hour −1 ) of ketamine (2.0 mg mL −1 ), xylazine (0.5 mg mL −1 ) and guaifenesin (50 mg mL −1 ) solution. Quality of anesthesia was assessed along with cardiorespiratory and biochemical measurements. Results Anesthetic induction took longer in GKX than in KP. The induction was considered good in 7/8 with KP and in 6/8 in GKX. Anesthetic recovery was classified as good in 7/8 animals in both treatments. Xylazine administration decreased heart rate (HR) in both treatments, but in KP the HR increased and was higher than GKX throughout the anesthetic period. Respiratory rate was higher in GKX than in KP. PaO 2 decreased significantly in both groups during the anesthetic period. Glucose concentrations [GLU] increased and rectal temperature and PCV decreased in both treatments. Arterial lactate [LAC] increased at recovery compared with all time points in KP. [GLU] and calcium were higher in GKX than in KP at recovery. Conclusion and clinical relevance These protocols induced significant hypoxemia but no other cardiorespiratory or metabolic changes. These protocols could be used to maintain anesthesia in donkeys, however, they were not tested in animals undergoing surgery.